Liquid-liquid extraction of gallium from Bayer process liquor using Kelex 100 in the presence of surfactants

The solvent extraction of gallium from a concentrated Bayer process liquor containing similar or equal to 450 g/l of Na2O, similar or equal to 80 g/l of Al2O3 and 190 +/- 20 ppm of gallium was investigated using 12 vol.% Kele x 100, a 7-alkyl substituted-8 hydroxyquinoline as extractant, 12 vol.% iso decanol as modifier and kerosene as diluent. At 1.0:1.0 organic to aqueous phase ratio and at room temperature, 80% of gallium was recovered in 3 h. I n order to improve upon the kinetics of extraction, the addition of surfact ants in the organic phase was studied. The addition of octylamine to the or ganic phase was found to reduce the rate of gallium extraction as well as i ts recovery. Additions of petroleum sulphonate up to 0.5 vol.% of organic p hase has increased the rate of gallium extraction by reducing the equilibri um time to 45 min along with 80% recovery of gallium. When the petroleum su lphonate addition was increased to 2.5 vol.%, the rate of extraction and th e recovery decreased significantly. The Versatic 10 volume percentage was s tudied at 1.0, 2.5, 5.0 and 10 by adjusting the kerosene volume percentage. Gradual increase in the volume percentage of Versatic 10 resulted in a dec rease in the equilibrium time, and the maximum recovery of 98% of gallium w as obtained at 2.5 vol.% Versatic 10 in 15 min. With further increase in th e Versatic 10 volume percentage, the gallium recovery was decreased. (C) 19 99 Elsevier Science B.V. All rights reserved.